Lithium-ion (Li+) secondary or rechargeable batteries are now the most widely used secondary battery systems for portable electronic devices. Conventionally, lithium-ion secondary batteries contain a liquid electrolyte, such as an organic carbonate carrying a lithium salt. Unfortunately, some organic carbonates decompose to form passivation layers called solid electrolytic interphase (SEI) layers on electrode or electrode material surfaces, decreasing the concentration of available electrolyte and thereafter decreasing the efficiency of the cell. Even more concerning, the organic materials used to form liquid electrolytes are inflammable leading to restrictions on the shipping, storage, and use of lithium-ion batteries.
Overcoming these detractions, lithium-ion batteries with solid phase electrolytes have been prepared. For example, U.S. Pat. No. 6,277,524 discloses a solid electrolyte for lithium batteries based on the general formula Li2 S—GeS2—X wherein “X” is at least one member selected from the group consisting of Ga2 S3 and ZnS, or Li2 S—SiS2—P2 S5. U.S. Pat. No. 8,075,865 discloses a class of lithium argyrodite materials for both primary and secondary storage. Continuing down this vein, U.S. Pat. No. 9,899,702 discloses a sub-class of lithium argyrodite thiophosphates for use in lithium ion batteries.
While these solid phase electrolytes show promise for use in lithium ion batteries, engineering cells with these solid materials requires further improvements. One continuing challenge is interphase boundaries between anodic and cathodic materials and the solid phase electrolyte.